1. Field of the Invention
The invention relates to a multi-channel implantable/ingestible telemetry system which offers major improvements in the electronic design of data links for biomedical or industrial use. More particularly, the design parameters for the telemetry system of the invention may be incorporated in a miniaturized multi-channel implantable/ingestible capsule for generating signals representing various physiological stimuli and capable of extremely stable DC signal measurement capability, low power consumption for all channels, insensitivity to battery voltage variation, and size for low cost in fabrication and manufacture.
2. Description of the Prior Art
Several examples of technologies that have already been implemented or seen experimentation within the context of implantable/ingestible devices include such devices as an implantable temperature monitor for the heart, commandable temperature capsules which transmit signals only in response to request for transmission, rechargeable/reusable capsules for animal work, and certain experimental designs for pill identification or calibration. Efforts have also been directed to gastrointestinal applications as, for example, monitoring CO.sub.2 in the gut in which case preferable design requirements include the ability to provide intermittent transmission and automatic shut-off at the end of useful life.
Therefore, there is the need, not taught in the prior art, for a completely designed and tested telemetry system having commercial as well as biomedical applications but principally intended for implantation into or ingestion by a human subject and offering flexibility and reliability when measuring parameters within the human environment with a minimum of interference therebetween.
Accordingly, an object of the invention is a multichannel device for collecting, amplifying and converting to useable information biological signals representative of a plurality of physical stimuli.
Another object of the invention is to fabricate a two-part system which inductively reads out from a controlled body environment a plurality of physiological signals.
A further object of the invention is to provide an implantable pill which has three independent channels for developing information from implanted sensors without interference.
Still a further object of the invention is to provide carrier and subcarrier modulation from voltage control oscillators having substantially no overlap or interference with each other in the course of generating a plurality of signals indicative of a human condition.
Yet a further object of the invention is the design of receiver electronics which can in principle be interfaced to biomedical long-range communication technologies such as cellular phones, or radio, to effect long-range telemetry.